The Wayanad wildlife sanctuary, the second largest in the state and part of one of the most important tiger landscapes, is facing a `Latin American' invasion these days. A rapidly proliferating invasive tree species ­ Senna spectabilis ­ introduced, arguably , as part of social forestry activities some 15 years ago poses a threat to wildlife and natural forest cover. The species, originally a native of South America, has established dominance over large swaths of the sanctuary , stifling almost all other plants in its vicinity and food availability for herbivores. Besides its ability for prolific seeding and early age reproduction, scientists have also noted the release of allelochemicals from it that impair the growth of other plants. The Asia-Pacific forest invasive species network (APFISN), a 33-nation alliance of Asia-Pacific Forestry Commission member-countries, has already sounded an alarm in this regard. “The tree is very aggressive and it rapidly displaces all native plant species. Its root exudates contain allelochemicals that affect the chemical pro file of the soil and hinder the growth of other plants. It even affects the germination of other seeds. We have observed that even grass doesn't grow in areas taken over by the tree,“ said Dr T V Sajeev, APFISN coordinator at Kerala forest research institute. “The species was introduced as an avenue tree as part of social forestry activities. It was a mistake, especially in an eco-sensitive area like Wayanad,“ he said. Sajeev said they were working on a project supported by the Food and Agriculture Organisation (FAO) of the UN to prepare protocols for its control. A survey to estimate the extent of its spread will be launched soon. The population of the species, numbering in lakhs, has also affected the free movement of animals. Roy P Thomas, wildlife warden, said the threat was severe in the Muthanga and Tholpetty forest ranges while the species has made inroads into Sultan Bathery forests. “The havoc caused is terrible. If left uncontrolled, it will completely dominate the sanctuary in another 10-15 years,“ he said. Experts at the forest research institute consider girdling or ring barking ­ of removing a strip of bark of the tree around the entire circumference of its trunk ­ to arrest its growth and flowering. They said no other sanctuaries in the state have been affected this badly. Officials, however, said they do not have any information of the social forestry wing resorting to mass planting of the tree. “We have not undertaken any mass planting of the tree in Wayanad but we will have to check if it was planted as part of any afforestation programmes,“ said Pradeep Kumar, chief conservator of forests (social forestry), Kozhikode.